1. Technical Field
The present invention relates to a roller bearing for supporting rolls in a rolling installation and a continuous casting installation, for example.
2. Background Art
A large number of rolls including work rolls, backup rolls, etc., are used in a rolling installation. A large number of rolls are used also in a continuous casting installation. These rolls are rotatably supported by roller bearings provided at their opposite ends. This roller bearing comprises: an inner ring fitted on a journal portion formed at roll end portion; an outer ring fixed on and supported by an installation-side housing (bearing box); and a number of rolling elements interposed between the inner ring and the outer ring.
In the above installation, since a large number of the rolls are used, the number of the roller bearings provided for supporting them is also large accordingly. Therefore, for example, when performing the maintenance operation of the above installation, a great labor for detaching the large number of roller bearings is required. Therefore, in order to enhance the maintenance workability, the journal portion is clearance-fitted with the inner ring of the roller bearing so that the roller bearing can be easily detached from the roll.
In the case where the inner ring of the roller bearing and the journal portion of the roll are clearance-fitted with each other, a so-called creep in which the journal portion and the inner ring rotate relative to each other is liable to occur. And besides, it is not premised that an outer peripheral face of the journal portion of the roll and an inner peripheral face of the inner ring slidingly move relative to each other, and therefore sufficient lubrication environment is not secured. Therefore, there has been encountered a problem that the journal portion of the roll and the inner peripheral face of the inner ring are much worn.
Therefore, there has been proposed a roller bearing in which a spiral groove for supplying grease between an outer peripheral face of a journal portion (roll neck shaft) of a roll and an inner peripheral face of an inner ring is formed on the inner peripheral face of the inner ring (see Japanese Utility Model Publication No. 62-147722 U).
FIG. 5 shows a roller bearing in which such a spiral groove is formed.
As shown in FIG. 5, this conventional roller bearing which is a multi-row conical roller bearing 21 comprises: a pair of inner rings 22 having inner peripheral faces to which a roll neck shaft B is inserted; two pairs of outer rings 23 disposed in an outside of the inner ring 22 in the radial direction of the inner rings 22; a spacer 23a interposed between the two adjacent outer rings 23 disposed at a center part in the axial direction of the roller bearing 21; a plurality of conical rollers 24 rotatably disposed between each inner ring 22 and each outer ring 23; an oil supplying hole 25 formed through the spacer 23a; annular recessed portions 26 formed between the pair of inner rings 22 and the roll neck shaft B at the center part in the axial direction of the roller bearing 21; an oil groove 27 communicating the recessed portions 26 with the oil supplying hole 25; and spiral grooves 28 formed respectively in the inner peripheral faces of the inner rings 22 and extending with a plurality of turns from the recessed portions 26 respectively toward opposite end portions in the axial direction of the roller bearing 21.
In the above roller bearing, grease is supplied to the oil supplying hole 25 from the exterior thereof, and this supplied grease in the oil supplying hole 25 is supplied to the spiral grooves 28 via the oil groove 27 and the recessed portions 26. As a result, contact faces between the roll neck shaft B and the pair of inner rings 22 are lubricated by the grease.